Field of the Invention
The present disclosure relates to an organic light emitting display panel and a method of manufacturing the same, and more particularly, to an organic light emitting display panel and a method of manufacturing the same, which use face seal technology for achieving narrow bezel configurations.
Discussion of the Related Art
Recently, flat panel displays (FPD) and other types of display apparatuses which have good characteristics such as thinness, lightness, and low power consumption are increasing in importance. Examples of display apparatuses include liquid crystal display (LCD) apparatuses, plasma display panels (PDPs), organic light emitting display (OLED) apparatuses, flexible displays, curved displays, etc. Recently, electrophoretic display (EPD) apparatuses are being used as well.
In particular, LCD apparatuses and organic light emitting display apparatuses including thin film transistors (TFTs) provide good results in resolution, color display, and image quality, and thus are commercialized as display apparatuses for notebook computers, tablet computers, desktop computers, smartphones, and various other electronic devices.
Organic light emitting display (OLED) apparatuses are self-emitting apparatuses, and have low power consumption, a fast response time, high emission efficiency, high luminance, and a wide viewing angle. Therefore, the organic light emitting display apparatuses are attracting much attention as the next-generation display apparatuses.
Generally, the lifetime of a panel for an organic light emitting display apparatus is determined based on certain factors, such as an operation lifetime and a shelf lifetime.
The operation lifetime denotes a period where the maximum luminance is reduced when driving a device (for example, an organic light emitting diode (OLED)). The operation lifetime can be determined based on impurities contained in an organic material, an interface between the organic material and an electrode, a low glass transition temperature (Tg) of the organic material, and oxidization of a device (for example, an OLED) by oxygen and moisture.
The shelf lifetime denotes a period during which characteristics of an emission area is gradually reduced by moisture permeation into the organic material despite the device not being driven.
The lifetime of an OLED is determined by a shorter lifetime value among the operation lifetime and the shelf lifetime.
Moisture denotes that which is introduced in a process of manufacturing a device (for example, an OLED), and moisture which permeates from the exterior into the manufactured device. In some organic light emitting display apparatuses, face seal technology is used for minimizing the permeation of external moisture.
FIG. 1 is a cross-sectional view schematically illustrating a configuration of an organic light emitting display panel 10 having a face seal structure according to a related art. FIGS. 2A and 2B are exemplary diagrams for describing a moisture permeation path based on a non-display area size in the organic light emitting display panel 10 having the face seal structure. The non-display area includes a bezel area.
Referring to FIG. 1, the organic light emitting display panel 10 includes a driving transistor Tdr which is on a first substrate 12, an OLED (denoted as “E”) which is connected to a first driving electrode 14 of the driving transistor Tdr, a passivation layer 15 which covers the entire surface of the first substrate 12 including the OLED E, and a second substrate 17 which is provided on the passivation layer 15. In this case, the first substrate 12 is closely adhered to the second substrate 17 with the passivation layer 15 therebetween. In such organic light emitting display apparatus, the passivation layer 15 and the second substrate 17 cover the entire upper surface of the first substrate 12, and thus, even when external force or impact is applied to the organic light emitting display apparatus, the organic light emitting display panel 10 is not easily damaged.
However, in such organic light emitting display apparatus having the face seal structure, a moisture permeation path could occur due to interface imperfections or defects of a non-display area including a bezel area. In this case, as illustrated in FIG. 2A, moisture permeates into the OLED E via a bank 16 and a planarization layer 13, which are disposed at an outermost portion of the organic light emitting display panel 10, along a moisture permeation path R which starts from a side surface of the passivation layer 15.
Particularly, in a case of implementing a narrow bezel in an organic light emitting display apparatus, since an anti-moisture film such as a barrier film is not provided in a non-display area, allowing for a moisture permeation path up to a certain length or distance should be secured for maximally delaying the permeation of external moisture.
However, as illustrated in FIG. 2B, in the organic light emitting display apparatus having the face seal structure, as the non-display area is reduced, the moisture permeation path R becomes shorter.
Therefore, a probability that moisture permeates into the OLED E via the bank 16 and the planarization layer 13 which are disposed at the outermost portion of the organic light emitting display panel 10 becomes higher.
Due to the permeation of moisture, a moisture permeability of the OLED E can worsen, and a lifetime of the OLED (E) is shortened. For this reason, the lifetime of the organic light emitting display apparatus according to the related art is shortened.